Shows anxiety about glacial ice (5)
I believe the answer is:
serac
'glacial ice' is the definition.
(serac is a section of ice on a glacier)
'shows anxiety about' is the wordplay.
'shows anxiety' becomes 'cares'.
'about' says the letters should be written in reverse.
'cares' written backwards gives 'SERAC'.
(Other definitions for serac that I've seen before include "icy pinnacle" , "glacial ice formation" , "Glacier ice pinnacle" , "mass of ice" .)